The present invention relates to a composite component and to a process for producing a composite component having a first component element and a second component element, the first component element and the second component element being connected with one another by an adhesive connection. The composite component may be a supporting part of a motor vehicle body.
It is known to arrange a structural element, i.e. a reinforcing element, in an area between an outer and an inner shell, particularly in the case of a motor vehicle body in its shell construction. In this case, the structural element may consist of a fiber-reinforced plastic material, such as a carbon-fiber-reinforced plastic, while the inner and/or outer shell may consist of steel. The structural element is connected with the outer and/or inner shell by way of a connecting adhesive as a result of an area connection. Such a component in the shell construction having a structural element is described in German Patent Document DE 102007010341 A1.
It is now an object of the present invention to create a composite component and a process for producing a composite component having a first component element and a second component element which are connected with one another by an adhesive connection, which permits a simple formation of locally limited adhesive points.
This and other objects are achieved by a process according to the present invention for producing a composite component having a first component element and a second component element, which are connected with one another by an adhesive connection. The process includes the steps of forming an adhesive cavity with the following substeps:
applying a thermally active plastic material to an adhesive connection side of the first component element and/or to an adhesive connection side of the second component element,
arranging the first component element on the second component element, a gap being formed between the adhesive connection side of the first component element and the adhesive connection side of the second component element, and
supplying heat such that the thermally active plastic material expands and forms a boundary in the gap between the first component element and the second one. The process further has the step of filling the formed adhesive cavity with an adhesive for the permanent connection of the first component element with the second component element.
The adhesive cavity forms a locally limited adhesive point or adhesive connection point between the first component element and the second component element. After its expansion, the thermally active plastic material forms a wall extending in the gap between the first component element and the second component element. The gap is a space between the first component element and the second component element.
Several adhesive cavities and therefore adhesive points may be formed in the composite component.
By the process according to the invention, the first component element and the second component element can be connected in a simple manner at a previously defined local point by use of an adhesive connection. In addition, this process makes it possible to create locally limited adhesive connections. As a result, adhesive is applied only to locally limited points, i.e. to local adhesive points. It is therefore not necessary to fill the entire gap between the first component element and the second component element with adhesive. This saves material, weight and costs. In addition, by supplying heat, the present process makes it possible that the second component element is prefixed at the first component element by the expansion of the thermally active plastic material. This has the advantage that the first component element with the second component elements can pass through further processes until the actual adhesive connection for connecting the second component element with the first component element is established. This is particularly advantageous when the first component element and the second component element jointly have to pass through process steps anyhow, which require a heating of the first component element together with the second component element. However, such a heating of the second component element with the first component element with the completely formed adhesive connection would be disadvantageous because an adhesive connection is thermally stable only within certain limits.
In the case of the process according to the invention, the first component element is preferably constructed of a first material and the second component element is constructed of a second material. The first material and the second material are different materials.
In particular, the first material and the second material have different thermal coefficients of linear expansion.
In the case of two materials with different coefficients of linear expansion, it is especially advantageous to create an adhesive connection which is more elastic than a connection by means of mechanical, form-fitting connection devices, for example such as bolts, screws or rivets.
Particularly preferably, the first material is made of plastic and the second material is made of metal. In the case of this pairing of materials, the problem of different coefficients of linear expansion occurs in many cases, which, however, can be solved in an appropriate manner by means of the present invention.
Naturally other pairings of materials, which are formed of the first material and the second material, are also contemplated. For example, the first component element may consist of steel, aluminum or plastic, for example, fiber-reinforced plastic. The second component element may, in turn, consist of aluminum, plastic, for example, fiber-reinforced plastic, steel or magnesium.
Preferably, the thermally active plastic material is further applied such that the thermally active plastic material, at least after the step of the supplying of heat, during which the thermally active plastic material expands, forms a closed boundary in the gap.
The thermally active plastic material can thereby be applied with interruptions, in which case these interruptions can be closed by the expansion of the thermally active plastic material when heat is supplied and can therefore form a closed bead.
As an alternative, the thermally active plastic material can already during the application be constructed in the shape of a closed bead, which forms the boundary.
According to the present invention, in the “supplying of heat” step, process heat is further supplied during a coating step of the composite component.
In particular, the heat is process heat which is necessary for drying the coating, and which is additionally used for the supplying of heat in order to activate the thermally active plastic material.
Thus, on the one hand, the process heat can be used for pre-fixing the second component element on the first component element, and, on the other hand, the filling of the adhesive cavity with adhesive can be carried out after the supplying of process heat, so that the process heat for drying the coating has no disadvantageous effect with respect to the adhesive connection.
The coating is preferably applied to the composite component in a dip coating process. However, other coating processes are also contemplated in connection with the present invention.
The first component element preferably is a hollow section, and the second component element is a reinforcing element which is arranged inside the hollow section. In this case, during the step of forming the adhesive cavity, the thermally active plastic material is applied to an exterior side of the reinforcing element and/or to an interior side of the hollow section.
The hollow section may further consist of a first hollow section component and a second hollow section component.
This facilitates an insertion of the reinforcing element into the hollow section. For example, the reinforcing element can first be inserted into the first hollow section component, and subsequently, the second hollow section component can be joined to the first hollow section component.
The hollow section may also consist of more than two hollow-section components.
In the “arranging of the reinforcing element in the hollow section” step, the reinforcing element is preferably arranged in the first hollow-section component, and then the first hollow-section component is connected with the second hollow-section component.
Particularly preferably, the composite component is a supporting part of a motor vehicle body.
The first component element, for example, the hollow section, and the second component element, for example, the reinforcing element, may have arbitrary shapes and cross-sections. When the composite component is, for example, used in a motor vehicle body, the first component element and the second component element may have the shapes and cross-sections customary there in order to meet requirements with respect to rigidity and stability.
The thermally active plastic material according to the present invention may by a permanently elastic foam, for example, of ethylene vinyl-acetate or ethylene butyl-acrylate.
A composite component according to the present invention has a first component element and a second component element which are connected with one another by way of an adhesive connection. A gap is formed between the first component element and the second component element, in which gap at least one locally limited adhesive cavity is formed, which is bounded by an adhesive connection side of the first component element, an adhesive connection side of the second component element as well as at least one wall of thermally activated plastic material. The adhesive cavity is filled with an adhesive for the permanent connection of the first component element with the second component element.
The gap is a space between the first component element and the second component element.
The composite component may be further developed as explained in connection with the process for producing a composite component.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.